The bellhousing bolts on the engines have different bolt patterns.
The bell housings on the saildrives are very different in depth from each other.
There is an obvious difference between a saildrive that accepts a Volvo engine compared to one that accepts a Yanmar engine.
With an adapter plate in replacement of a bell housing and some carefully machined parts you might be able to bolt those two units together.
It's going to be like bolting a Chevy engine to a Ford transmission and putting it in a Fiat.
Why bother, it will be a lot of work for a mickey mouse job.

the yanmar will not bolt up the hole in the hull so it will require some glass work. if you are limited on time the best bet is to do the mod with the yanmar saildrive bed and glass it into the hull as per yanmar specs. it is not a hard job if you have good access but it is a technical one to mate the bed to your hull. modifying the mount could be done but there would be some trial fitting and and design work to do and that can take longer then just doing it the proven way. remember every time you change one thing on a boat it will require you to change ten other things you did not think about.

Changing sail drives from one manufacturer to another isn't for the faint of heart. Especially if both money and time are issues.

First, I have to ask why you picked this particular boat if you hated Volvos? Or why you selected a boat which utilizes a sail drive? Although the sail drive engine positioning allows boat designers more flexibility when laying out a boat (yeah you get more room), I don't know one single person who has one who has anything good to say about them. The maintenance on sail drives is a killer. The specs say you have to change the oil every 100 hours which means a haul out. Same when replacing the zincs....and those boots do fail.

Now you want to toss the Volvo for a Yanmar? Look, anything can be done if you're able to spend enough money or have enough time. You have apparently have neither.

The way I see it, in the end, you're going to have to construct your own fiberglass engine bed, which of course has to be flawless as the sail drive boot covers a hole in the water.... and strong as a 3GM has amazing torque for it's size and will tear cheesy glass work apart instantaneously.

Changing sail drives from one manufacturer to another isn't for the faint of heart. Especially if both money and time are issues.

First, I have to ask why you picked this particular boat if you hated Volvos? Or why you selected a boat which utilizes a sail drive? Although the sail drive engine positioning allows boat designers more flexibility when laying out a boat (yeah you get more room), I don't know one single person who has one who has anything good to say about them. The maintenance on sail drives is a killer. The specs say you have to change the oil every 100 hours which means a haul out. Same when replacing the zincs....and those boots do fail.

Now you want to toss the Volvo for a Yanmar? Look, anything can be done if you're able to spend enough money or have enough time. You have apparently have neither.

The way I see it, in the end, you're going to have to construct your own fiberglass engine bed, which of course has to be flawless as the sail drive boot covers a hole in the water.... and strong as a 3GM has amazing torque for it's size and will tear cheesy glass work apart instantaneously.

I hope that boat was a real good deal.

Oh man, what a bunch of fear mongering.

I've already owned the boat for 5 years and I'm not sure where you read I hated Volvo's.. The 1978 MD11 needs a rebuild, so it was time to find other options. I picked up a 3GM with 191hrs on it, for $3000 and now i just have to install it. No big deal, I'm just here to throw some ideas around.

I'm not here to debate the whole saildrive issue either but, Morris Yachts installs them on their new Ocean Series 48GT boats. What are they selling for new these days.....1.5 million?

I think you have gotten some fairly good answers here regarding what you are trying to accomplish.
But, you have already dumped $3000 dollars into an engine that you knew would require a lot of modifications to work, ie; more mods+more time=more money.
If you are short on cash and time why didn't you have the old engine rebuilt at a fixed cost and time?
That would seem like an equally expensive but easier route to have taken.

Very tough job, with high potential for dubious results. Even if you get in to fit, issues with alignment, vibration, strength of modification craftsmanship will all be potential interruptions in your cruising plans.

It would have seemed that using the $3k to do your own overhaul would be a much safer bet and the timeframe is reasonable. Farm out the pieces that you don't have the tools/skills to do. Replace all the rest of the wearable parts. It must be doable for someone with the mechanical aptitude to take on a project like the one contemplated. The results would be much more predictable and reliable.

Rebuilding a 1979 MD11, an engine they don't make parts for anymore? No offence but that's terrible advice. I'm not here to debate my decision to buy the Yanmar, I simply wondered if anyone else has tried this.

I actually just went outside and dropped the Yanmar saildrive into the Volvo engine bed and snapped some pictures. It looks like a nice fit, I'd just have to drill and tap new bolt holes.

The difficult part will be designing engine feet to reach the front mounts. I might be able to make it work with custom aluminum c-channel brackets.

Beta does this all the time, I just haven't found anyone who has done it with a Yanmar.

that looks like a good fit. I agree, I would not rebuild an md 11 and its the 110s saildrive parts that are the hardest to come by. I would think the engines mounts will be easy once you have the saildrive mounted. the mounts in this case are not that critcal because all the do is hold the weight of the engine on one end there is no alignment issue for the propshaft. I say start tapping those holes and it will all fall into place. that is going to be a great setup

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